package leetcode.剑指offer;

import java.util.Stack;

public class 用两个栈实现队列09 {

    Stack<Integer> stack1;
    Stack<Integer> stack2;

    public 用两个栈实现队列09() {
        stack1 = new Stack<>();
        stack2 = new Stack<>();
    }

    public void appendTail(int value) {
        stack1.push(value);
    }

    public int deleteHead() {
        if(stack2.isEmpty()){
            if(stack1.isEmpty()) return  -1;
            while (!stack1.isEmpty()){
                stack2.push(stack1.pop());
            }
        }
        return stack2.pop();
    }
}
